Regulator for centralized refrigerating

ABSTRACT

A pressure or flow regulator for food refrigeration systems and installations for distributing fluid under pressure. The regulator is particularly intended for centralized refrigeration systems having a group of compressors mounted in parallel and delivering fluid refrigerant to refrigerated cabinets which are periodically defrosted. The regulator has two interconnected bellows in an enclosure filled with a fluid having a low coefficient of expansion. One of the bellows is deformable by changes in pressure at the low pressure side of the compressors, and resulting deformations in this bellows are transmitted by the fluid in the enclosure to the other bellows, which actuates micro-contacts controlling the starting or stopping of the compressors.

United States Patent [1 1 Charineil et al.

[451 Aug. 6, 1974 REGULATOR FOR CENTRALIZED REFRIGERATING [75] Inventors: Pierre Charmeil, Montreuil; Michel Debieuvre, Nogent/Marne, both of France [73] Assignee; S A IQL fConstructiqns Ispthermiquies Bontorne, Vinc ennes, France [22] Filed: Apr. 17, 1972 [21] Appl. No.: 244,580

[30] oreign Application Priority Data Apr. 23, I971 France 71.14522 [52] US. Cl 200/83, 62/226, 62/228, 62/510 [51] Int. Cl. H01h 35/40 [58] Field of Search 62/196, 215, 226, 227, 62/228, 510; 200/83 J, 81-.4, 83 D [56] References Cited UNITED STATES PATENTS 2,237,574 4/l94l Parsons 62/226 2,985,732 5/l96l Russell 200/83 .l 3,260,8[6 7/1966 Schad 200/83 .1 3,350,896 ll/l967 Hamish 62/228 Primary Examiner-Meyer Perlin [5 7] ABSTRACT A pressure or flow regulator for food refrigeration systems and installations for distributing fluid under pressure.

The regulator is particularly intended for centralized refrigeration systems having a group of compressors mounted in parallel and delivering fluid refrigerant to refrigerated cabinets which are periodically defrosted. The regulator has two interconnected bellows in an enclosure filled with a fluid having a low coefficient of expansion. One of the bellows is deformable by changes in pressure at the low pressure side of the compressors, and resulting deformations in this bellows are transmitted by the fluid in the enclosure to the other bellows, which actuates micro-contacts controlling the starting or stopping of the compressors.

. 9 Claims, 4 Drawing Figures t PATENTEU AUG SHEUI [If 3 PATENTEB Am; slam .SHEET 3 OF 3 REGULATOR FOR CENTRALIZED REFRIGERATING The setting up of a modern supermarket requires the installation of central refrigerating equipment capable of maintaining a plurality of refrigerated cabinets at different temperatures which depend upon the nature of the foods to be preserved.

The refrigerating systems used are of the compression type whch supply the refrigerated cabinet with a fluid refrigerant. When a refrigerated cabinet is supplied by a compressor in this manner, it is necessary to defrost the cabinet periodically so that the equipment functions properly; defrosting by means of an exterior medium at positive temperature is achieved by stopping the compressor unit for an hour or two, which means that when a compressor supplies a refrigerated cabinet at positive temperature, 50 percent of its power is lost.

A loss of energy of this kind cannot be tolerated in high-power installations such as those used in supermarkets and it is for this reason that central refrigerating equipment based onthe principle described below has been designed.

As shown diagrammatically in FIG. 1 of the annexed drawing, an assembly comprising an appropriate number p of compressors arranged in parallel supplies a container 12 with high-pressure fluid refrigerant by way of a condenser 11, and each refrigerated cabinet 13 is supplied from this container through a solenoid valve 14 controlled by a thermostat 15; arranged in series with the valve is a defrosting programmer 16. At all times the compressor assembly must be provided with the power necessary for ensuring that an installation comprising n refrigerated cabinets 13 functions properly.

The mode of operation is as follows:

It is assumed that the system operates at a constant evaporation temperature of "10C, which means maintaining a constant pressure in the intake pipe 17. This pressure may be 39 psig, for example, whereas the fluid refrigerant is that usually employed and known by the nameR 22.

If at a particular moment t, n-5 refrigerated cabinets for example are in service, a certain power P is provided by the central installation. If at the moment t t, n-4 cabinets are in service, that is to say one cabinet more, a power P A P will be required, and if only the power P is provided, the intake pressure will rise; it will act on a regulator which will send a signal that causes a further compressor to start up.

Conversely, if the numer of refrigerated cabinets in service is reduced, the intake pressure diminishes and the regulator sends a signal which causes one of the compressors to stop.

Thus, the maintenance of the intake pressure at a constant level is ultimately achieved by automatically varying the number of compressors-in operation, whatever the number of refrigerated cabinets brought into or put out of service, and despite the fact that these refrigerated cabinets are themselves thermostatically controlled.

In a system operating on a similar principle, use is made of at lesast one multi-cylinder short-circuiting compressor, the power, intake and compression in certain of these cylinders. being reduced by the action of the regulator. In this modified arrangement, mechanical losses in the order of 5 percent have to be accepted.

The advantages of these central refrigerating systems are considerable and, in brief, are as follows: reduction in the power that needs to be provided, assembly of the equipment in the factory, decreased consumption of electric power, and greater reliability in operation.

It is however obvious that correct functioning of the equipment depends upon efficient control.

It is known practice to use as a regulator a pressure gauge having a minimum .contact and a maximum contact fitted at the intake of the compressors; depending upon which of the contacts is energized, a programmer is caused to rotate in one direction or the other for the purpose of stopping or starting the groups of compressors; a drawback of a regulating system of this kind is that it comprises elements which are difficult to regulate and which frequently break down.

With a view to achieving greater reliability, it has therefore been proposed to use an electronic system comprising a pressure pick-up incorporating a strain gauge fitted at the input of a multi-stage amplifier producing impulses for controlling the compressors. This regulating system is efficient but it carries the considerable drawback of being extremely costly.

The present invention relates to a regulator which is of simple construction and therefore inexpensive, and which operates in a reliable and uniform manner.

The object of the invention is a regulator for central refrigerating equipment of the kind described above, said regulator being characterized in that it consists mainly of a first deformable bellows, subjected to the changes in pressure in the intake pipe of the compressors of the central equipment, the deformations in which bellows are transmitted to. a second bellows having a considerably shorter stroke than the first for the same change in pressure, this second bellows being fitted with means which, depending upon the direction in which deformation occurs, closes or opens microcontacts whereby the compressors are started up or stopped.

Other features forming part of the invention will emerge from the following description which relates to the annexed drawing illustrating a non-limiting example of the construction of such regulator.

IN THE DRAWING:

FIG. 1 is a schematic diagram of a refrigeration system including a plurality of compressors connected in parallel and controlled sequentially by a regulator in accordance with the invention.

FIG. 2 is a section through the portion of the regulator which contains the two deformable bellows.

FIG. 3 is a view of the means actuated by the upper bellows for starting or stopping the groups of compressors.

FIG. 4 shows a modified form of the circuit diagram of FIG. 1, with the refrigrated cabinets operating at different temperatures.

The housing accommodating the moving elementsv of the regulator and illustrated in FIG. 2 comprises a steel cylindrical portion 20 at the ends of which are welded two flanges 21; fitted to the lower flange is a plate 22 which is secured in a fluid-tight manner with the aid of an O-ring 36 made of neoprene; the plate is clamped on to the flange by means of screw-bolts which are passed through the holes 24 and 25. A plate 23 is fitted in the same wayto the upper flange with the aid of the sealing ring 36 and the holes 24 and 26. 1

Inside the cylindrical portion 20, a bronze bellows 28 is secured to the central portion of the lowerplate by silver soldering, this bellows communicating, by way of the central'openign 27 in the plate, with the intake pipe (17, FIG. 1) of the compressors; collapse of the bellows is limited by an interior stop 29 of cylindrical form.

Below the central portion of the upperplate 23, there is similarly fixed a second bronze bellows 30 having a smaller diameter and a greater length than the bellows 28. This second bellows communicates byway of the axial opening 31 in the plate, with a cylindrical port 32 which is welded to the plate and in which is contained a linear ball-bearing unit 33 heldin position by a forcefit.

With the aid of the valve 34and the air-cock 35, the cylindrical portion 20, sealed in a'fluid-tight manner, is completely filled with a fluid having a low coefficient of expansion, such as the special break oil known by the name Lockheed.

The means for actuating the regulator for startingor stopping the groups ofv compressors are illustrated in FIG. 3.

Two threaded rods 40 each constituting a post are fitted by their lower ends in two of the pairs of diametrically opposed holes 24 and 26 in the upper plate 23 and its flange (FIG. 2).

Secured transversely to the. top of the posts 40 by means of nuts 41 is an iron element 39 which contains two horizontal grooves 43 along which are distributed a plurality of micro-contacts 42, each of which is able to open or close the circuit of the corresponding contactor of a motor compressor; only one of these microcontacts is shown in the drawing.

The size of the ball-bearing unit 33 and the opening 31 (FIG. 2) is such that a ground steel rod 37 can slide with negligible friction within the bearing 33, said rod resting by its lower end 48 on the base of the bellows 30. Between the posts 40, this rodcarriesa steel counterweight 38 on which are mounted a row of steel screw-threaded rods 47 each of which has a tapered tip 45 at its upper end. The position of the tapered end can be adjusted in the vertical direction by means of a nut 46 which causes the rod 47 to be moved up or down in a cylindrical hole 44 in the counterweight 38. The latter may be of rectangular form, as illustrated, to facilitate adjustment of the engagement positions of the tips of the rods 47.

At a predetermined moment, each of thesetapered portions 45 may move into engagement with the microcontact 42 which is fitted vertically above said tip; only one of the rods 47 is shown in the drawing.

The mode of operation of the regulator shown in FIGS. 2 and 3 is as follows:

The interior of the bellows 28 is always under the pressure thatJobtains inside the intake pipe 17.

A slight change in the intake pressure of the compressors causes a slight displacement of this bellows by expansion or compression; the resultant change in volume is transmitted through the oil in the cylindrical portion to the upper bellows which in turn contracts or expands to a compensating extent. The size of teh two bellows is such that for any change in length of the lower bellows the change in length of the upper bellows in the opposite sense is approximately ten times greater; it is a simple matter to adjust the amount of the It-will be seen that, depending upon the power re- I quired by the refrigerated cabinets, one or more micro contacts can be engaged or disengaged at any 'moment and one or more of the corresponding compressor groups can be started or stopped.

It should be noted that the counterweight 38, the weight of which together with the ground rod 37 is in the order of 12 kg, may be provided with cavities for accommodating further weighting material; it then becomes possible by adding weighting material to the counterweight, or removing such material therefrom, to adjust in the best possible manner the level of the evaporation temperature of a given installation.

The regulator that has been described can obviously be used in connexion with groups of compressors, with or without a pressurereducing means (not shown, but identified for convenience by the letters RP). An installation may for example, comprise four groups of compressorsG G G and G the first group G, being equipped with a pressure-reducing system RP. The power supplied by the central equipment willbe increased by using,in succession, the following combinations of compressors:

. G with RP Consequently, eight micro-contacts will be necessary, and it is possible to space them 'overa total engagement distance of 20 mm. Preferably, the points of engagement of the contacts will be slightly underadjusted in relation to the power reduction so as to avoid as far as possible over-frequent starting up and where the refrigerator groups are to be operable at two temperature levels, the Applicants recommend the use of central equipment using two-stage compression as illustrated diagrammatically in FIG. 4, in which the same reference numerals are used as in FIG. 1 for designating like elements; the defrosting programmer and the thermostats are not shown in the simplified diagram.

The refrigerated cabinets, of an appropriate number n, are regarded as operating at l0C, whereas a further cabinet 49 arranged in parallel operates at 30C with a solenoid vavle 50. The pressure in the intake pipe 7 is established at 37 psig by the R 22 fluid refrigerant; the pressure is 9 psig in the pipe 51 whereas at the outlet of the compressors the pressure is raised to 210 psig.

At the inlet to the compressors it is necessary to raise the pressure in the pipe 51 to 37 psig; an intermediate compression stage 52 will then be used, and only a single regulator will be necessary for maintaining the pres-' sure in the pipes (7, 53)'at a level of 37 psig.

The regulator of the invention can be used in refrigerating installations at all temperature levels and with any fluid refrigerant; if the latter is ammonia gas, it is preferred to use bellows made of stainless steel; the regulator can be used in all cases where it is desired to control the flow of a fluid by influencing its pressure, or conversely to control pressure by influencing flow. It may be fitted with a scale thermostatic system to increase the number of levels controlled by the thermostat.

We claim:

1. In a regulator for use in centralized refrigerating equipment consisting essentially of a plurality of compressors arranged in parallel for supplying fluid refrigernat through conduits to a plurality of refrigerated cabinets and receiving said fluid refrigerant from said cabinets through an intake conduit, the improvement in said regulator consisting essentially of a first bellows in fluid communication with said intake conduit and deformable by pressure changes in said intake conduit and a second bellows in fluid communication with said first bellows, having a greater stroke than said first bellows for a given pressure change, said second bellows being deformable under the influence of deformation in said first bellows, a plurality of switches including micro-contacts connected to control the starting up or stopping of respective ones of said compressors, said second bellows including means to actuate said microcontactssequentially in response to said deformation.

2. A regulator according to claim 1, wherein said first and second bellows are accommodated in a fluid-tight enclosure, having cylindrical walls whose longitudinal axis is vertically oriented and having upper and lower cover-plates, said first bellows being secured above said lower cover-plate, and said second bellows being secured beneath said upper cover-plate, the space between said walls of the enclosure and said bellows being completely filled with a fluid having a low coefficient of expansion.

3. A regulator according to claim 2, wherein said second bellows has a base supporting a rod axially slidablethrough said upper cover-plate with negligible friction, which rod supports a counterweight outside said enclosure, said -counterweight having an upper horizontal face carrying a plurality of rods for closing and opening said micro-contacts.

6. A regulator according to claim 2, wherein said first and second bellows are made of brass.

7. A regulator according to claim 3, wherein said counterweight has provision for additional weights to be fitted thereto.

8. A regulator according to claim 1, wherein said first bellows is fitted with an interior stop limiting collapse thereof.

9. A regulator according to claim 2, wherein said first and second bellows are made of stainless steel.

'7 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 32 1 2 Dated August 6 1974 Inventor(s) Pierre Charmeil and Michel Debieuvre It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Correct item [73] to read, Assignee: S.A.R.L. "Constructions Isothermiques Bontami", Vincennes, France-- and Column 5, lines 12-13, correct "refrigernat' to read --refrigerant-.

Signed and sealed this 4th day of February 1975.

(SEAL) Attest:

McCOY M. GIBSON JR. C. MARSHALL DANN Attesting Officer Commissioner of Patents FORM PO-IOSO (10-69) USCOMWDC WWW fi U,S. GOVERNMENT PRINTING OFFICE: 19! 0-366-33L i UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIGN Patent No. 3 32g 1 I32 Dated August 6 1974 Inventofls) Pierre Charmeil and Michel Debieuvre It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Correct item [73] to read, -Assignee: S..A.R.L. "Constructions Isothermiques Bontami", Vincennes, France-- and Column 5, lines 12-13, correct "refrigernat" to read refrigerant.

Signed and sealed this 4th day of February 1975.

(SEAL) Attest:

McCOY M. GIBSON JR. C. MARSHALL DANN Attesting Officer Commissioner of Patents FORM PO-1050 (10-69) USCOMWDC 6o376 P69 U.S, GOVERNMENT PRINTING OFFICE: I969 O-366-334, 

1. In a regulator for use in centralized refrigerating equipment consisting essentially of a plurality of compressors arranged in parallel for supplying fluid refrigernat through conduits to a plurality of refrigerated cabinets and receiving said fluid refrigerant from said cabinets through an intake conduit, the improvement in said regulator consisting essentially of a first bellows in fluid communication with said intake conduit and deformable by pressure changes in said intake conduit and a second bellows in fluid communication with said first bellows, having a greater stroke than said first bellows for a given pressure change, said second bellows being deformable under the influence of deformation in said first bellows, a plurality of switches including micro-contacts connected to control the starting up or stopping of respective ones of saiD compressors, said second bellows including means to actuate said microcontacts sequentially in response to said deformation.
 2. A regulator according to claim 1, wherein said first and second bellows are accommodated in a fluid-tight enclosure, having cylindrical walls whose longitudinal axis is vertically oriented and having upper and lower cover-plates, said first bellows being secured above said lower cover-plate, and said second bellows being secured beneath said upper cover-plate, the space between said walls of the enclosure and said bellows being completely filled with a fluid having a low coefficient of expansion.
 3. A regulator according to claim 2, wherein said second bellows has a base supporting a rod axially slidable through said upper cover-plate with negligible friction, which rod supports a counterweight outside said enclosure, said counterweight having an upper horizontal face carrying a plurality of rods for closing and opening said micro-contacts.
 4. A regulator according to claim 3, wherein said micro-contacts are aligned horizontally on an element carried above said enclosure said rods each having a tapered tip, the height of each tip above said counter-weight being adjustable whereby each micro-contact is individually actuable in dependence upon a characteristic predetermined deformation of said second bellows.
 5. A regulator according to claim 4, wherein said second bellows has a stroke approximately ten times greater than the stroke of said first bellows for any given pressure change.
 6. A regulator according to claim 2, wherein said first and second bellows are made of brass.
 7. A regulator according to claim 3, wherein said counterweight has provision for additional weights to be fitted thereto.
 8. A regulator according to claim 1, wherein said first bellows is fitted with an interior stop limiting collapse thereof.
 9. A regulator according to claim 2, wherein said first and second bellows are made of stainless steel. 